If $a + b + c = -6$ and $x + y = 5$, what is $9y + 9x - 10a - 10c - 10b$ ?
Answer: $= -10a - 10b - 10c + 9x + 9y$ $= (-10) \cdot (a + b + c) + (9) \cdot (x + y)$ $= (-10) \cdot (-6) + (9) \cdot (5)$ $= 60 + 45$ $= 105$